GeeBee Posted October 16 Report Posted October 16 27 minutes ago, aviatoreb said: Why is it that turbine engines are so much very much more expensive? At first blush they seem like a simpler concept. I know the thing that has to do with creating single crystal material is intensely complex but is that technology in a standard PT6 or a RR300? I just dont understand why a turbine engine is 5 or 10 times as expensive as a piston aviation engine which is already 10 times as expensive as the equivalent car engine (that last I get because of economy of scale - and the car engine has better precision in build). Well I would love to have an RR500 (that mythical engine that Mooney never got built) hanging on the end of my nose - but in reality if I had the money to think about that I wouldnt likely do it - the turbine Mooney already exists - I would more likely buy a used TBM700. And after all it is a Mooney - M in TBM is for Mooney. It's a more modern Mooney 301 - which was an early 1980 Mooney concept plane that eventually morphed and lead directly to the TBM700. Materials. Think how much an IO-360 would cost if the entire engine were constructed of exhaust valve material instead of simple cast aluminum and steel. In addition, the casting and forging have to be several higher orders of precision. You can cast a cylinder head fairly rough and machine it down substantially into a usable part. Not so with a compressor blade. If you remember the compressor disk off UAL 232 you get an idea of the level of purity, quality of material and manufacturing required. 2 Quote
carusoam Posted October 16 Report Posted October 16 Has the recent war economy in Europe started building modern turbine engines in our scale? they have been building large drones for long distance flying. they want to carry a heavy payload, a long distance… and low flying is better than flying in the FLs for radar avoidance… See if Honeywell is showing anything… P&W partnership? HON powers the Reaper drone… 900hp may be a bit oversized still, for non-Rocket Engineering mod owners… (touchy subject, so don’t let me start a fire accidentally. ) Best regards, -a- Quote
MikeOH Posted October 16 Report Posted October 16 1 hour ago, GeeBee said: Materials. Think how much an IO-360 would cost if the entire engine were constructed of exhaust valve material instead of simple cast aluminum and steel. In addition, the casting and forging have to be several higher orders of precision. You can cast a cylinder head fairly rough and machine it down substantially into a usable part. Not so with a compressor blade. If you remember the compressor disk off UAL 232 you get an idea of the level of purity, quality of material and manufacturing required. Well, let's think about material cost. A quick Google shows that nickel superalloys are used in turbines. I found that Inconel 600 alloy is roughly $45/kg; titanium is a similar cost. Aluminum is down around $2.50/kg. So, around 20X the cost. At that ratio, let's say the aluminum is free. An IO-360 weighs around 300 pounds, and a PT6A, depending on configuration, can be as much as 500 pounds. Worst case, 500 lbs. X $20/lb. is $10,000. So, no, I don't think it's the material costs. I'd agree the precision required likely adds considerable cost but I still struggle with the enormous cost difference. 1 1 Quote
carusoam Posted October 16 Report Posted October 16 Machining those funky alloys takes a bit more time and effort… fortunately, they are known entities… not like when I was in college… back in the day, a man called a lathe operator, actually ran a machine called a lathe… machinists were awesome… Best regards, -a- 2 Quote
Schllc Posted October 16 Report Posted October 16 3 minutes ago, MikeOH said: Well, let's think about material cost. A quick Google shows that nickel superalloys are used in turbines. I found that Inconel 600 alloy is roughly $45/kg; titanium is a similar cost. Aluminum is down around $2.50/kg. So, around 20X the cost. At that ratio, let's say the aluminum is free. An IO-360 weighs around 300 pounds, and a PT6A, depending on configuration, can be as much as 500 pounds. Worst case, 500 lbs. X $20/lb. is $10,000. So, no, I don't think it's the material costs. I'd agree the precision required likely adds considerable cost but I still struggle with the enormous cost difference. Raw material cost is a small portion of the actual cost of "different' material. casting, forging, machining and heat treating those alloys is considerably more expensive. They are harder with wildly different properties, and I am certain there are more parts requiring a tighter tolerance, it isn't apples to apples. I would bet that the biggest factor is the number of engines. They just don't make that many. Quote
Brandt Posted October 16 Report Posted October 16 8 minutes ago, MikeOH said: Well, let's think about material cost. A quick Google shows that nickel superalloys are used in turbines. I found that Inconel 600 alloy is roughly $45/kg; titanium is a similar cost. Aluminum is down around $2.50/kg. So, around 20X the cost. At that ratio, let's say the aluminum is free. An IO-360 weighs around 300 pounds, and a PT6A, depending on configuration, can be as much as 500 pounds. Worst case, 500 lbs. X $20/lb. is $10,000. So, no, I don't think it's the material costs. I'd agree the precision required likely adds considerable cost but I still struggle with the enormous cost difference. Just proving that it takes a lot of money and technology for a Bonanza to approach the performance of a Moooney 1 4 Quote
MikeOH Posted October 16 Report Posted October 16 2 minutes ago, Schllc said: Raw material cost is a small portion of the actual cost of "different' material. casting, forging, machining and heat treating those alloys is considerably more expensive. They are harder with wildly different properties, and I am certain there are more parts requiring a tighter tolerance, it isn't apples to apples. I would bet that the biggest factor is the number of engines. They just don't make that many. No doubt those issues are factors but they boil down to labor/machine time...I struggle to understand what would be a factor of 10 difference in those operations vs. casting/forging/machining/heat treating for a piston engine. I think your comment about volume of engines is likely the real explanation. Quote
GeeBee Posted October 16 Report Posted October 16 28 minutes ago, MikeOH said: Well, let's think about material cost. A quick Google shows that nickel superalloys are used in turbines. I found that Inconel 600 alloy is roughly $45/kg; titanium is a similar cost. Aluminum is down around $2.50/kg. So, around 20X the cost. At that ratio, let's say the aluminum is free. An IO-360 weighs around 300 pounds, and a PT6A, depending on configuration, can be as much as 500 pounds. Worst case, 500 lbs. X $20/lb. is $10,000. So, no, I don't think it's the material costs. I'd agree the precision required likely adds considerable cost but I still struggle with the enormous cost difference. I am missing your math. You say an IO-360 weighs 300 pounds (136kg) and a PT6A is 500 pounds (226kg). Then you say aluminum is $2.50/kg and Inconel 600 is $45/kg. So in your raw terms the material costs of an IO-360 is $340 (136x2.50) and a PT6A is $10,000 (226x45). So the material costs of a PT6A is 29 times an IO-360. So compared to a new IO-360 at 100K a new PT6 at 29X is 2.9 million. We know that it is about 1 million new so the PT6A is quite a value based upon your math. Quote
MikeOH Posted October 16 Report Posted October 16 1 minute ago, GeeBee said: I am missing your math. You say an IO-360 weighs 300 pounds (136kg) and a PT6A is 500 pounds (226kg). Then you say aluminum is $2.50/kg and Inconel 600 is $45/kg. So in your raw terms the material costs of an IO-360 is $340 (136x2.50) and a PT6A is $10,000 (226x45). So the material costs of a PT6A is 29 times an IO-360. So compared to a new IO-360 at 100K a new PT6 at 29X is 2.9 million. We know that is about 1 million new so the PT6A is quite a value based upon your math. Your claim was that the cost difference was due to material cost. I.e. how expensive an IO-360 would be if made of jet engine materials. So, I looked at the difference in material cost. Conclusion: there is ONLY $10,000 worth of material in a PT6A, or an IO-360 made of the same material (actually $6,000 at 300 lbs). Therefore, the price difference between a $1,000,000 PT6A vs. a $100,000 IO-360 is NOT due to material cost. 1 Quote
GeeBee Posted October 16 Report Posted October 16 20 minutes ago, MikeOH said: Your claim was that the cost difference was due to material cost. I.e. how expensive an IO-360 would be if made of jet engine materials. So, I looked at the difference in material cost. Conclusion: there is ONLY $10,000 worth of material in a PT6A, or an IO-360 made of the same material (actually $6,000 at 300 lbs). Therefore, the price difference between a $1,000,000 PT6A vs. a $100,000 IO-360 is NOT due to material cost. No, you are taking me out of context. My claim was material and and I said, "In addition, the casting and forging have to be several higher orders of precision." Again, when you look at the forging of that disk on a CF6 vs forging a crankshaft, they are worlds apart in materials, material casting, forging methods and precision. The average crankshaft probably has 6 inclusions that caused that CF6 disk to come apart. Quote
MikeOH Posted October 16 Report Posted October 16 1 minute ago, GeeBee said: No, you are taking me out of context. My claim was material and and I said, "In addition, the casting and forging have to be several higher orders of precision." Again, when you look at the forging of that disk on a CF6 vs forging a crankshaft, they are worlds apart in materials, material casting, forging methods and precision. The average crankshaft probably has 6 inclusions that caused that CF6 disk to come apart. Context? You literally said, "Materials. Think how much an IO-360 would cost if the entire engine were constructed of exhaust valve material instead of simple cast aluminum and steel." Also, you seem to ignore that in my original response I acknowledged that the higher precision would add cost; i.e., I agreed with you on that point! I still maintain that difference does not fully explain the enormous difference in the completed engine price. I think @Schllc comments about quantity are probably far more likely to be the explanation. Quote
GeeBee Posted October 16 Report Posted October 16 Well Lycoming produces 3000 engines per year of all sizes, P&W produces 1000 PT6A engines per year. Quote
Schllc Posted October 16 Report Posted October 16 2 hours ago, GeeBee said: Well Lycoming produces 3000 engines per year of all sizes, P&W produces 1000 PT6A engines per year. I think we are all more or less saying the same thing. Piston engines are simple compared to a turbine (with regard to manufacturing processes and raw materials). I actually made a complete running three cylinder piston engine for a thesis in college on a cnc machine. It functioned and ran, but was a functional static display. I did 100% of it with my own hands and it took me 2 semesters working about 10 hours a week. Pistons are easy. The only way to drive down the cost of turbine engines would be to make them in mass quantities. What the breaking point would be to significantly reduce the price, I don’t know, but the more complicated it is, the more it will cost in small quantity. How much do you think it would cost to make 1,000 iPhones vs 50 million? Btw, our lawnmower piston engines shouldn’t cost 100k either!! 2 Quote
Pinecone Posted October 16 Report Posted October 16 Precision is part of it. If nothing else, our piston engines run at 2700 RPM. PT-6 core runs at 21,000 - 30,000 RPM. And at close tolerances of the rotating parts to the fixed parts. Quote
Will.iam Posted October 16 Report Posted October 16 1 hour ago, Schllc said: I think we are all more or less saying the same thing. Piston engines are simple compared to a turbine (with regard to manufacturing processes and raw materials). I actually made a complete running three cylinder piston engine for a thesis in college on a cnc machine. It functioned and ran, but was a functional static display. I did 100% of it with my own hands and it took me 2 semesters working about 10 hours a week. Pistons are easy. The only way to drive down the cost of turbine engines would be to make them in mass quantities. What the breaking point would be to significantly reduce the price, I don’t know, but the more complicated it is, the more it will cost in small quantity. How much do you think it would cost to make 1,000 iPhones vs 50 million? Btw, our lawnmower piston engines shouldn’t cost 100k either!! They don’t cost 100k but the bill from the lawyers and litigation cases that they have to pay out amortized over time is added to our bill. 1 Quote
EricJ Posted October 17 Report Posted October 17 8 hours ago, aviatoreb said: Why is it that turbine engines are so much very much more expensive? High mechanical stress (centrifugal force, plus force the blades are producing), plus tight tolerances. The tolerances are tight to prevent leakage around the outer perimeter of the blade disks, and those tolerances have to be maintained under stretch due to centrifugal force, heat cycles, etc., etc. The hot sections have crazy mechanical and thermal requirements, so none of it is easy to make or inexpensive. Even as an A&P if I were maintaining one myself, a hot section inspection could get very expensive just due to parts costs alone, and you can't skimp or you'll regret it. And the costs are high even on the non-rotating parts, like fuel and oil systems, etc., etc. They just cost a lot, and they're expected to work reliably for many heat cycles over many thousands of hours, so the engineering is difficult but if it is a working airplane or otherwise flies a lot, the costs are distributed over a long time, presumably with the associated reliability benefits. 3 Quote
exM20K Posted October 17 Report Posted October 17 @MikeOH consider that the puny turbochargers on my acclaim cost $6500 each o/h exchange (or somewhat less than that if someone here does you a solid ona spare turbo). I’ve no idea what they are new, but it’s probably $8-12,000. A PT6 of any flavor is many times more complex and has vastly more metal which can tolerate combustion temps. As for our expensive lawnmower engines, adding up all the components, and labor, put 20-30% manufacturer’s margin in there, it is not shocking to me that a new or factory o/h TSIO550 is on the far side of 100 AMU’s. I wish it were not so, of course. -dan Quote
MikeOH Posted October 17 Report Posted October 17 31 minutes ago, exM20K said: @MikeOH consider that the puny turbochargers on my acclaim cost $6500 each o/h exchange (or somewhat less than that if someone here does you a solid ona spare turbo). I’ve no idea what they are new, but it’s probably $8-12,000. A PT6 of any flavor is many times more complex and has vastly more metal which can tolerate combustion temps. As for our expensive lawnmower engines, adding up all the components, and labor, put 20-30% manufacturer’s margin in there, it is not shocking to me that a new or factory o/h TSIO550 is on the far side of 100 AMU’s. I wish it were not so, of course. -dan Well, I think the price for puny AIRCRAFT turbochargers is also ridiculous! Do you honestly think a new aircraft turbo is really made of that much more expensive materials, machined to that much tighter tolerances, and is that much more reliable to justify an over $10,000 premium? (No, I'm not going to put a Summit racing turbo on my plane!) 1 Quote
Shiroyuki Posted October 17 Report Posted October 17 Rather than putting in old turbine engine with more horsepower into piston planes which already have big bore cylinders, it’s probably more realistic to expect a mid body or even short body Mooney with a PBS TP100 conversion. 241 hp weighing only 135 lbs, that’s 150-200 lbs extra useful load comparing a IO360, also comparing to a naturally aspirated engine it will come with better high altitude performance. Imagine a 20J at 120000ft cruising at 180 knots… fuel burn also isn’t bad according to the manufactures number, .86lbs/hp/hr, that comes out to 18.4 gallon at 150hp (75% of 200hp). By going higher it can burn even less fuel. It is indeed double the fuel burn of a IO360, but with a future where avgas supply will likely decline, it might be a plausible mod. Also in Europe and canada jet fuel price is significantly cheaper than avgas so the total fuel cost will be much closer. If it is used to replace the tsio550 in the acclaims, the fuel economy might looks better. Cost for the engine is unknown, but a similarly sized turbojet, the PBS TJ100, used by Sonex Subsonex jet is $75000, considering there will be more components like gears box, 100K would be my guess? Quote
A64Pilot Posted October 17 Report Posted October 17 If you saved a large amount of weight in the nose with a lightweight engine it’s likely you will need ballast to compensate. Maybe on a long body putting the batteries in the nose and removing the charlie weights would do it? If so then you save even more weight than the engine alone, win, win. Mid bodies maybe not? The Thrush for example was a Piston airplane converted to turbine, it ended up with two batteries when it only needed one and about 200 lbs of #9 bird shot in ballast tanks to get the CG back within safe limits. We ballasted each aircraft individually to the absolute max allowable aft CG. I extended the engine mount 11 inches on the H-80 and lost the 200 lbs of lead and the extra battery, but it’s very easy to get into trouble aerodynamically just by extending the nose, I got away with it by making the nose perfectly round and as small as possible “needle nose”. Just extending the nose very often will require a bigger tail, that adds weight and your back to ballasting the nose and could end up gaining weight. On the Thrush and I assume a Mooney would be similar 1 lb on the tail due to the arm required 3 lbs of nose ballast to offset it. Quote
carusoam Posted October 18 Report Posted October 18 Nose ballast can be a good thing… Four blades with Beta mode, in traditional aluminum… the talented hub, can be a bit weighty… My mythical house on a 2k’ runway can use the improved stopping distance… Best regards, -a- Quote
A64Pilot Posted October 19 Report Posted October 19 It’s probably being pedantic, but I think Beta is misunderstood, it’s near flat pitch as in min or no thrust, reverse is well, reverse and is what is used to stop and aircraft on landing or to back one up. The Pilatus Porter is allowed to use Beta on approach, that’s how they get that stupid steep descent, but they can’t do that in reverse. I assume but do not know that they have a gate that prevents accidental reverse, but as I have never seen ones throttle quadrant that is just a guess. Quote
guyjill Posted October 20 Report Posted October 20 I owned the only Allison 250-17 Turbine Lancair ES.... it was a blast to fly but the cruise speed was about the same as the Super ES with the IO-550 with twice the fuel burn and 7x the cost for an overhaul. Stick with what you have... 5 Quote
M20F Posted October 20 Report Posted October 20 I am going to start flying helicopters to save money. 1 4 Quote
MikeOH Posted October 20 Report Posted October 20 28 minutes ago, M20F said: I am going to start flying helicopters to save money. I tried that....it doesn't work 1 Quote
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